JavaScript

How to check if a string is alphanumeric in JavaScript using a regular expression, including a reusable helper and notes on empty strings and Unicode.

Reliably get JSON from an LLM in JavaScript with OpenAI structured outputs and a Zod schema, instead of prompting for JSON and parsing fragile model text yourself.

What the double question mark (??) means in JavaScript: the nullish coalescing operator, how it differs from ||, and the ??= assignment shorthand.

Create a small LangChain JavaScript agent with one custom tool using createAgent, tool, and a Zod schema, with a runnable end-to-end example.

A minimal OpenAI function calling example in JavaScript using the Responses API and a local tool, including the two-step call-the-tool then answer loop.

Use OpenAI structured outputs with a Zod schema to get typed, app-ready JSON back from an LLM in JavaScript, with the schema doubling as your TypeScript types.

A minimal Vercel AI SDK tool calling example using generateText, tool, stepCountIs, and a Zod inputSchema, with the tool loop handled for you.

Build a simple RAG system in Node.js with OpenAI and plain text files. No vector database, no embeddings: pass docs into the model and get answers.

A practical guide to what the double exclamation mark (!!) does in JavaScript, how it differs from Boolean() and the ?? operator, with real examples.

Add a property to an object in JavaScript with dot notation, square brackets, the spread operator, and Object.assign. Plus dynamic keys, conditional properties, nested objects, adding several at once, and TypeScript.

How to create a random alphanumeric string of a certain length in javascript, with a simple helper and a more secure crypto-based version.

How to check if a JavaScript array contains a string with includes, some, and indexOf, and how to check if a string contains any element from an array.